Environmental impacts by input of substances in landscapes of the District (Bezirk) of Leipzig,Germany     

Prof. Dr. G. Haase  Dr. L. Händel  Dr. Chr. Nagel  Dr. Chr. Opp  Dr. R. Zierath 《GeoJournal》1990,22(2):153-165

Problems of landscape and resource protection resulting from the intensification of land-use can be mastered only by intersectoral planning and a land management considering (landscape-)ecological principles right from the beginning. In the district of Leipzig ecological studies in the '80ies have focussed on:

1. Determination of the regional pattern of atmospheric immissions;
2. Registration of heavy metals in soil and vegetation;
3. Soil compaction, soil erosion;
4. Study of stress indicators in the aeration zone and in the top-most aquifer in order to examine barrier effects in the percolation process.

First results are discussed.  相似文献   

Stratabound ore deposits related to synsedimentary tectonics: South-West Sardinia (Italy) and Sierra de Aracena (Spain); a comparison     

A. Arribas  T. Bechstädt  M. Boni 《International Journal of Earth Sciences》1990,79(2):373-386

Deposition of stratabound Zn-Pb-Ba ores in the Lower Cambrian carbonates in South-west Sardinia show a distinct relation with the prominent tensional tectonics in the area. A part of the mineral deposits are syngenetic (sedimentary-exhalative), other massive sulfides and/or barite are early diagenetic. Other occurrences (MVT) are from early to late-diagenetic. They are mostly confined to matrix- and cementbreccias which might be dependent on the Cambrian tectonics. The Precambrian-Lower Cambrian (?) carbonates occupying the core of the Aracena anticline, at the boundary between the provinces of Huelva and Badajoz (South-west Spain), are also an important metallotect for Zn-Pb-Ag-Ba mineralization. The ores at Aracena are stratabound (to stratiform) (Sedex) and occur as disseminations or layers in a volcano-sedimentary sequence with carbonate intercalations. Both the carbonate intervals and the ores show evidence of synsedimentary tectonics, like slumpings, slump breccias and neptunian dykes. Their deposition most likely occurred in a subtidal environment controlled by faults. Apparently, in South-west Sardinia and in the Sierra de Aracena, both sedimentary evolution and ore deposition were strictly related, and conditioned by several pulses of tensional tectonics.  相似文献   

The mean coronal magnetic field determined from HELIOS Faraday rotation measurements     

M. Pätzold  M. K. Bird  H. Volland  G. S. Levy  B. L. Seidel  C. T. Stelzried 《Solar physics》1987,109(1):91-105

Coronal Faraday rotation of the linearly polarized carrier signals of the HELIOS spacecraft was recorded during the regularly occurring solar occultations over almost a complete solar cycle from 1975 to 1984. These measurements are used to determine the average strength and radial variation of the coronal magnetic field at solar minimum at solar distances from 3–10 solar radii, i.e., the range over which the complex fields at the coronal base are transformed into the interplanetary spiral. The mean coronal magnetic field in 1975–1976 was found to decrease with radial distance according to r ^?α, where α = 2.7 ± 0.2. The mean field magnitude was 1.0 ± 0.5 × 10 ^?5 tesla at a nominal solar distance of 5 solar radii. Possibly higher magnetic field strengths were indicated at solar maximum, but a lack of data prevented a statistical determination of the mean coronal field during this epoch.  相似文献   

Including the Urban Canopy Layer in a Lagrangian Particle Dispersion Model     

Stöckl  Stefan  Rotach  Mathias W.  Kljun  Natascha 《Boundary-Layer Meteorology》2022,183(1):1-33

Boundary-Layer Meteorology - When wind blows over the ocean, short wind-waves (of wavelength smaller than 10 m) are generated, rapidly reaching an equilibrium with the overlying turbulence (at...  相似文献   

The distribution and relative toxic potential of organic chemicals in a PCB contaminated bay     

Sundberg H  Tjärnlund U  Kerman G  Blomberg M  Ishaq R  Grunder K  Hammar T  Broman D  Balk L 《Marine pollution bulletin》2005,50(2):195-207

For reliable monitoring of environmental improvement, the PCB contaminated bay Orserumsviken on Sweden's Baltic coast was investigated prior to remediation. We examined PCB congener patterns and the relative toxic potential of PCBs in extracts of three matrices: bottom sediment, settling particulate matter and the dissolved phase (obtained from semi-permeable membrane devices). Congener patterns were similar in all matrices. Three fractions were isolated from the extracts: (1) aliphatic and monocyclic aromatic compounds (MAC-fraction), (2) dicyclic aromatic compounds (DAC-fraction), including PCBs, and (3) polycyclic aromatic compounds (PAC-fraction), including PAHs. Total extracts and fractions were injected into newly fertilised rainbow trout eggs. At larval stage, hepatic EROD activities were quantified. Though high, the PCB contamination could explain only an estimated 1-5% of the total EROD induction. The order of EROD induction potential was: total extract > PAC-fraction > DAC-fraction > MAC-fraction in all matrices, suggesting that in Orserumsviken PACs made a larger contribution to the EROD induction potential than PCBs and other DACs.  相似文献   

Paramètres statistiques de la houle au large de la côte sud-aquitaine     

Stéphane Abadie  Rémi Butel  Hélène Dupuis  Christophe Brière 《Comptes Rendus Geoscience》2005,337(8):769-776

Statistical parameters of waves on the south Aquitaine coast have been determined by comparison of two datasets: in situ local measurements on a short duration and numerical simulation outputs from the WAVEWATCH III model over a period of 6 years and 9 months. Data and simulation results are well correlated in the case of the significant wave height, whereas in the case of the peak periods $(T_{\mathrm{p}})$ and directions $(D_{\mathrm{p}})$, this correlation is lower. This is due respectively to the intrinsic unstable nature of $T_{\mathrm{p}}$ and the narrow distribution of $D_{\mathrm{p}}$. An adjustment of simulation data on measurement is then used to give an evaluation of the wave statistics for the southern fraction of the French Atlantic coast. Eventually, the relationships between the three statistical variables $(H_{\mathrm{s}},T_{\mathrm{p}},D_{\mathrm{p}})$ are analysed in order to determine representative sea states. The classification obtained shows the predominance of swell regimes, distributed on a very narrow angular sector over wind sea regimes. To cite this article: S. Abadie et al., C. R. Geoscience 337 (2005).  相似文献   

Collisions in self-gravitating clouds of planetesimals     

K. A. Hämeen-Anttila 《Earth, Moon, and Planets》1983,28(3):267-303

A theory of partially elastic collisions is constructed for frictionless planetesimals in an arbitrary gravitational field. The non-zero size of the particles and the influence of gravitational encounters are included. The equations for a self-gravitating rotationally symmetric disk or ring are written in an explicit form. Such systems turn out to be bimodal in the same sense as the Keplerian systems, i.e. there are two kinds of stable configurations which may co-exist in adjacent regions without disturbing the mechanical equilibrium. The transitions from one mode to another can also occur at essentially smaller values of the optical thickness than those previously found for Saturn's rings: in one of the numerically studied cases the transition from the dense to the rarefied mode occurred at the optical thickness 3×10^?5 while the reversed process corresponded to a higher value, 10^?2. The difference illustrates the dependence of the transition on its direction. The characteristic S shape which several authors have found for the relation between the viscosity and the optical thickness in Keplerian systems becomes more complicated if the contribution of self-gravitation increases. In some cases the stable solutions also imply a certain minimum value of the optical thickness.  相似文献   

Hydrographische Bibliographie     

Fr. Model  H. Mädler 《Ocean Dynamics》1967,20(3):131-156

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On the latitude drift of sunspot groups and solar rotation     

Jaakko Tuominen  Juhani Kyröläinen 《Solar physics》1982,79(1):161-172

The N-S drift of sunspot groups has been studied in a different way than previously, using positions of recurrent groups of the years 1874–1976. The existence of the meridional motions, the general shape of the drift curves, and the dissimilarity between these curves around sunspot maxima and minima, are all confirmed. In addition, also for the angular velocity of the Sun the same material gives differences around the times of sunspot maxima and minima.  相似文献   

The Effects of Streamers on the Shape of the K-Coronal Spectrum     

Nelson?L.?ReginaldEmail author  Joseph?M.?Davila  O.?C.?St.?Cyr 《Solar physics》2004,225(2):249-265

We conducted an experiment in conjunction with the total solar eclipse of 21 June 2001 in Lusaka, Zambia, to obtain the K-coronal spectrum simultaneously from multiple locations on the solar corona. Then we matched the observed K-coronal spectra with the modeled K-coronal spectra to determine the coronal electron temperature and its bulk flow speed. Here the models assumed a symmetric and isothermal corona with the coronal electron flowing away from the Sun at a constant flow speed. We were able to make remarkable matches between the observations and the models. In this paper we will try to explain how the anomalies in the matches could be accounted for with the introduction of streamers in the K-coronal spectral models.  相似文献